The problem lies in finding a machine I want. There's eBay, where you can find the ones you like for a semi-reasonable price as long as you can personally drive out and pick it up from the ass-end of Florida or Northern Canada. There are a few places online that will ship them across North America, as long as you don't mind paying five times more than standard for even a used machine (and that doesn't even include shipping costs). There are plenty of small stores that sell a limited stock for reasonable prices, but once again you have to be within 50 miles of them, and they're all several states away.
Right now the only thing I've been able to find is some big arcade auction/expo thing that's coming to Dallas at the end of May, but it sounds like kind of a madhouse and there's no guarantee of quality... you can go out at 8 AM before the auctions start to kick the tires, so to speak, but if you don't know how to spot flaws, bad repairs, etc. with the naked eye then you're pretty much setting yourself up to be ripped off.
EDIT: AAAAAAHHH!! When it rains, it pours... found someone in Mesquite, and he's selling both Twilight Zone AND Addams Family for reasonable prices. But I only have the money and space for one! *beats head on desk*